Pulverized fuel combustion



May 17, 1932. J. G. COUTANT PULVERIZED FUEL COMBUSTION 3 Sheets-Sh eet 1Filed March 17, 1927 INVENTOR GM (3m ATTORNEY May 17, 1932. J. G.COUTANT PULVERIZED FIUEL COMBUSTION Filed March 17.

1927 3 Sheets-Sheet 2 INVENTOR W0 6' ATTORNEYS- May 17, 1932. J. G.COUTANT 1,858,451

' PULVERIZED FUEL COMBUSTION Filed Mar zh 17, 1927 3 Sheets-Sheet 3INVENTOR- Jo'jg QaM W ATTORNEY Patented May 17, 1932 UNITED STATESPATENT OFFICE JAY GOULD COUTANT, OF NEW YORK, N. Y., ASSIGNOR TO-FURNACE ENGINEERING COMPANY, INC., F NEW-YORK, N. Y., A CORPORATION OFNEW YORK runvaarznn rum. COMBUSTION Application filed March 17, 1927.Serial No. 176,137.

IQ connection with certain features hereof equivalent fluent fuel couldin some cases be substituted.

General objects of the present invention include: To improve efliciencyin firing fur-,

,, naces with pulverized fuel, while increasing convenience of operationand control, prolonging-the life of the furnace, and minimizing theupkeep cost; also to afford suchcontrol over the combustion aspractically to eliminate or minimize certain drawbacks existing inmethods in furnaces heretofore known. Further and more specific objectsand advantages of the present invention will be pointed out inthehereinafter following description of several embodiments therefor, orwill be understood to those skilled in the subject matter of combustion.The present application constitutes a partial continuation as to certainfeatures dis- :w closed in each oftwo prior applications filedrespectively March 5, 1925, Serial No. 13,322 and October 5, 1925,Serial bio-60,435, both relating to .pulverized fuel combustion, eachshowing several embodiments of the invention therein disclosed, certainof which embodiments'are. i'ncludedherein as parts of the presentapplication, as will be hereinbelow further referred to. Saidapplication 13,322 has now been patented, February 26, 1929, No.1,703,814. The invention hereof consists in the novel features ofapparatus, combination, arrangement, operation and construction hereinillustratedor described except so faras claimed in the priorapplications.

In the accompanying drawings Fig. 1 isa vertical section, partly in thenature of a diagram,'of a water tube boiler and furnace embodyingtheprinciples of the present invention, this figure correspondingsubstantially with Fig. 3

of said prior application No. 60,435; and Fig. 1 is a skeleton frontelevation of certain pipes and headers, while Fig. 2' is a detailvertical section taken substantially on the line 2--2 of Fig. 1.

Fig. 3 is a view similar to Fig. 1, but showing a different embodimentof the invention, and corresponding substantially with Fig. 4 of my saidPatent 1,7 03,814. Fig. 4 is a partial vertical section of still anotherform of embodiment of certain. features hereof; .and Fig. 5 a section atright angles thereto taken on the line 5-5 of Fig. 4. Figs. 6,- 7, 8 and9 are figures generally similar to Figs. 1, 3 and 5 but showing variousmodified embodiments of the features of invention.

It is to be understood that throughout the drawings many details andconnections are shown diagrammatically, without attempt to conformaccurately to practical embodiments,-

as furnace engineers will well understand the principles and how toapplythem.

Referring first to the embodiment of Figs. 1 and 2 this shows acombustion chamber 10 laterally surrounded by a front wall 11, rear wall12, and side walls 13, while at the upper I front is shown an arch 14;the chamber bottom will be subsequently described in greater detail. Theboiler is shown as of the type composed of water tubes 15, and it may beof any well known type. water at this point and hereinafter itisintended to include water either in li uid form or as steam, unlesswater in liqui form is specifically prescribed. H The present inventionmay be applied to a boiler furnace or steam' generator of substantiallyany type,

fire tube, water tube or other type, whether for stationary, locomotiveor marine use.

In using the term I For. p1 1rposes of illustration a boiler of the 1 3cross drumgtype' is shown in the. drawings',..the 1 druin lti beingshown above the boiler'yYan'dfi i the boiler? being provided with firstand front of theifirst baffle 17 and below the s'econd 'bafileglS' isjindicated' an ashspace or pocket w ere; I ticle-ior'ashes'o'fcombustion, or a portion of them, which tend-toiascendjfromthe com-'bustion chamber throughthe boiler; and herefnbel'ow will be-desc'ribed ameans: of removing the'ashes accumulating in the space l9-fand utilizingthem," i

' l is providedjjwith a special formof furnace- Ibottomeihbodying.theprinciple of my novel.

tom is preferably inclined as-in said-prior application, but inthepresent'e'mbodiment' ";,the bottom or floor is formed in: separateinclined floor 'portions21 and 22;,at' the front a andrear-respectively, 1 23 between their lower ends constituting an openingor chute extending preferably the entire width of the'boiler and servingto discharge ashes downwardly into the closed .or sealedashchamberorpocketto.be described. V 1 f Since-the illustrated'front andrear-11001- diiierentarrangement and=use,'the' front floor portion/21'will be describedffirst, although and bothfioorportions. being watercooled.

tubes-25 'These are circulation tubes prefer'ably in circulation withthe boiler, an'dajre shown extending.=; across thegfio'orin sliohamanner that each tube is inclined; Th'ejtubes Lare preferably closelyspaced ga'cross theen-y tire 'widthfofthe'boilen and their upper endsmay 1 be; united}byi'anfexterior', header-26; -S team or hot water:generated-in the hoes 21 is h Pip i27-ilsadinga pwardly dvconstituting-the lower header fora series of tubes '28.constitu tin awater wall in the up per part ofthe com' ustionichamber. Thesewalltube's28-are in turn conneeted by atop header29 which is shownconiiected by apipe 30 with a; suitable part of thesteamspace'of I; -,the;boiler suchasthe rear or upper' boiler] I header, from which the generated steamtrayels the usual "passagesfinto the drumwaterto the water'flo'o'r 21-isshown eflected by tending into the chamber 1 for purposes ftobedescribed If "In; accordancef wiith myZ-Patent 1,703,814

secondlbaiiles or walls 17 and' 18 compelling e the products ofcombustion to travel agtorimply that theactual tubes are bare, but thattous path tdthe final outlet and stack; In

high'heat conducting. power fromthe combustion space to the watercirculating in the ay accurm'ilate the finer solid par- 7 upper surface,better adapted for tl1e" clearing, removing or shedding'of ashes andother solid matters falling or settling-upon the The lowerfend of thecombustion chamber floor. The overlying cover may becomwater' bottom or'floor a made the ,subject of v V e 1 tubes, so asto insure high rate ofheat-conclaim-in my said Patent 1,703,814. The-bot (l-notion, the floorthu's absorbing large tion space,.this absorbed heat being taken up with.a gap or. passage tion, while adding materially to the-evaporation ofthe boiler, the extraction of radiant time operating to take down thetemperature portions 2Iand 22318 shown of somewhat thus inturnpermitting the furnace and boiler to be operated at greatlyincreased rating without production of excessive temperatures and theconsequent difficulties in slagging and otherwise.

It is sometimes desirable ,to provide-for manifestly thetwo'fl floor orbottom portions Cooperate-in that they mutually converge, giving ahopper shape b'ottom',i discharging centrally through 'the opening'or'ohute 23,

The; front On the other hand itmay be intermittently by a valve 40. .Th

will thus, a cend tothe header-26firom' which ashes by gravity} Thec'hamber'is preferably I stantial uantity of-ash discharged from the.

furnace p formed between a front 'wall- 43 and rear wall 16. The supplyor downward flowofcthe' 31/leading-from the drum to a'lower the floortubes 25, or

I I means, such as a sluice of running water or tube-extensions 33 exrather the downwa'r the vehicle or ashf receptacle 46 mounted ion thefloor tubes25 are'directly exposed to'the, radiant heat of con'1bustion,This does not. "7' the arrangement is such that the floor affords tubes.A heat conducting; cover ;;35'is indi-'' cated overlyingthetubes,andthisis prefer,

able noton-lyg'a sprotecting thetu'be's from 1 direct injury, but.affording a 'sm'oothor fiat heat from the combustion space at the samewithin the furnace,ameaningjbo ththe general or meantemperature and-theexisting tern peratu-re in the hottest or combustion'zone,

respect to L maintained constantly open, but adjustable y in position toregulatethe discharge of ash.

I e'. ash vchamber is below or. lower than 1 d the disc'harge'opening23- so as to receive ottom.- vThe chamber is shown" by the circulatingwater, which thus, keeps the floor sufliciently cool to prevent destructhe delivery opening orch,ut e- 23 avcon'trol device suchv asithe gate37; ',This'-'may. be

ids

closed, to receive ashes, and opened to dump them. When the ash'chainber is sealedIthe'- gate may bejentirely omitted. A connection38 is shown from the ate 'to a motor 39-1whi'c 1h y r. v

in'the'form of a sealed pocket or it-afford V v ing, receiving space toaccommodate a sub 44 and at its endsgthe side walls of theffurjnface,"-At itsjlower' endthei ash chamber or, 5;. pocket is shown providedwith;afldumpingfilfi device or ash gate 45, which may-be operatedintermittently at will to discharge the accumulated ashes into; anyknown conveying ber may be. substantially protected from being meltedand slagged by the radiant heat of the flames, bytheir removed positionor distance from the flames, by the shieldin character of the floorstructure above, an

' by the additional expedient of the adjustable gate 37 in the chute 23.The opening 23 is a restricted passage to the enlarged ash chamber, andis itself cooled and protected.

The ash pit hereof is preferably also exteriorly sealed, exceptduring/the occasional dumping operations, so that inflow of air throughthe chamber and floor opening is not maintained, and thus permitting thefloor opening or chute to be maintained continuously open, the furnacefloor thus functioning in the combustion, as already described, whilearranged to discharge ashes downwardly intothe enlarged ash chamber,whence they are disposed of intermittently or continuously. Anadvantageous arrangement is the location of the ash chamber 42 at aninside position, that is not in front of or behind the furnace, butbeneath the furnace floor and between the wall lines of the furnace. Theash pit, and the chute leading 'down into it, may both extend the entirewidth of the furnace, constituting a very effective ash disposal systemwithout impairing the functioning of the water floor.

Among the permissible variations is the provision of a water trough or.sluice beneath the ash chamber instead of the intermittent dumping floor45 discharging into a wheeled car 46. Thus Fig. 3 shows the bottom ofthe ash chamber 42 formed into a vessel or sluice 48in which is showna'body of water 49, which may be still water, drawn ofl occa sionally,or may be running water passing under a Water seal-wall forprogressively removing. ashes while excluding inflow of air.'Besidesmooling the ashes a function is performed 'by the provision ofwater in the ash chamber, namely' the formation of steam,

which passes back through the chute 23 into the combustion chamber,operating as an inert gas or vapor to dilute the combustion gases andthus assist keeping down the tem perature of the furnace ,during periodsof high rates of combustion and service. A similar result may beobtained inthe Figxl embodiment by means of a water spray 50 locatedabove the ashes in the chamber 42. Regulation of the s rayingaction willregulate the quantity 0 steam delivered into the combustion space.Regulationmay further be effected by adjusting-the position of the ashgate 37, since the wider open this gate is maintained the greater willbe the amount of radiant heat entering the ash chamber and .thereforethe greater the rate of evaporation therein,

Another feature, in connection with the ash chamber, is the coolin ofthe ashes therein by .water tubes carried into the chamber. In Fig. 1this refers to the downward extensions 33-of the floor tubes 25, alsoportions of the opposite tubes where extended down below the floor. Ineither case the tubes may be carried down further into the ash chamber,

to'increase the cooling efiect, on the same principle. These circulationtubes, lining the floor opening 23 and a portion of the ash chamber areadapted to absorb quantities of radiant heat and thus effect coolingoperations which will serve to prevent slagging at these points.

An improved feature in respect to the ash chamber hereof is theillustrated subdividing of the. chamber lengthwise into sections orsubchambers, thus eliminating the difficulties of maintaining a singlechamber the full width of the furnace and avoiding the difficulties. ofdumping therefrom. Thus passing to Fig. 2, a shape of chamber isindicated consisting of a series of small ash chambers 42, formed bydividing the full length of the chamber byvmeans of inclined walls orash bridges 52, the apexes of which are substantially below the entranceinto the floor opening 23, as indicated by the apex line 53 in Fig. 1;With this arrangement we have substantially converted the elongatedchamher into a series of small ash hoppers 42*,

' and this enables the use of a number of small separate discharge gates45 at the bottoms of the respectivehoppers,,and each gate may be rovidedwith a power device or piston 54 or opem'n and closing the gate at willor automatica 1y. The ash bridges 52 may be constructed of refractorymaterial, without cooling means, since each bridge is protected not onlyby its removed position from the heat of the flames, but by theproximity of the cooling watertubes 33 extended through the ash chuteinto the ash chamber,- in conse-.

quence of which the bridges will. not be subject to injury from theradiant heat, and the.

descending ashes will not be liable to melt or slag upon the bridges orin the chambers.

When the vessel 48 in Fig. 3 is used as a trough an endless-chain dragdevice 51 may be used for clearing the ash sludge longitudinally fromthe vessel; In this fi ure the floor tubes 25 and 25 are shown are, butthey may be covered with heat absorbing and conducting material as withFigs. 1 and 2,

or the baretubes maybe flattened or square" I to afford 'a substantiallyflat or smooth heat absorbing surface facing the flames.

For introducing fluent or pulverized fuel or coal into thefurnaceinjecting devices of various sorts may be employed. In Fig. 1 is-'indicated a fuel burner .56 of advantageous character. This'comprisesarrefra'ctory enclosure cont'anung a mixing and combustlon space 57. Thepulverized coal, mixed with air, may be admitted by a plurality oftransverse inlets 58 converging upon an axial point within the chamber,while supplemental air of combustion may be admitteclaxially by anadjustable air valve device 59 supplied through. air passages 60; froma'blower 61.

. The fuelis supplied through pipes62 .from

a pulverizer"63- .which in turn may be fed from an overhead coal hopper64;. This forced. draft mixing type of burner gives instantaneousignition. The combustion air andthe'fuel meet at right angles, withpreliminary combustion, and are thereaftermixed and burned in-theconfined space 57 surrounded by brick walls, from which space itdischarges into the. main com'b 'lstion'cham-- ber 10. It will-beunderstood that a series of burners maybe arrangedacros s one of thewalls of the combustion chamber. The

. flames enter the main chamber forming a hot zone and thus passupwardly through the cooled part of the chamber and thence into thepassesof thev boiler. The combustion is partially effectedin theconfined chamberof the burner, and is instantaneouslycompleted as itexpands into. a sort-of, flameless combustion in the main chamber. Sucha burner is preferably used horizontally; as shown, and is advantageousforlarge boiler furnaces, s1nce 1t permits practically unlimited ratesoflcombustion, due to the brick sur;

rounded initial restricted. combustion. space.

The described combustion operation embodies one of the featurescovered'inpriorapplication No. 60,435, the combustion existing first ina hightemperature zone, in-the hottest part of the chamber and furthestremovedfrom the boiler, thence passinginto 'a-following or temperaturereducing zone andfrom there into the boiler. It will beIobserved'thatthe I lowerpart of the combustion chamber '10fis surrounded only;refractory walls, thus promoting .and preserving a very high tem'fi isbelow the melting perature and insuring complete combustion. The nexthigher or following zone. is a cooled zone due to the circulationtubes..2 8, and-in passing through this zone the gases have'theirtemperature "lowered substantially, so that before reaching the boilerthe temperature ing slagging of. ash upon the boiler." Water screens maybe interposed 'in the .-'.-upgoing gases, as willbe later referred to.Inlieu of the burners 56 shown in Fig. 1 may be employed ordinaryburners comprlsing nozzles 66 as shown in Fig. 3. A

I .of the furnace and a series of these is indicated across the frontcorrespondmg series acr'oss-the'rear. Each pointof ash, prevent-1 watersupplied through t is found that forcible jets of the burner nozzles'broadly in said PatentNo. 1,703,814 con- .sisting in the regulation ofthe temperature .ofthe-furnace or combustion zone by varying the heatabsorbing surface -exposedto the flames. This particularly refers to thewater bottom-as constituting ineffect a portion of .the boiler directlyexposed to the radiant heat. By adjusting the extent of exposure thereofthe regulation of the entire combustion operation is permitted. Thus inperiods of high service the entire water bottom can be maintainedexposed to the Iflames thus absorbing much radiant heat and increasingthe effective direct exposed surface of the boiler. This permits agreatly enlarged fuel combustion rate without producing excessivetemperatures in the combustion chamber, the greater rate of fuelcombustion in turn producing a proportionate in J crease 1n evaporation,notonly at the direct exposed water surfaces, but throughout'the boiler.As in the prior application, this Is shown herein effected by allowingthe water bottom or floor? to become shielded by accumulating ashes,intimes of normal or subnormal rating or operation, while clearing olfthe ashes so? as to expose the floor, either more thoroughly or morefrequently, during times of high service; this operation being availablein those embodiments where thebottom slope is relatively gentle and not"so steep as'to be self discharging. Apart from.the-regulation, eitherform of bottom serves the. function of absorbing radiant heat,permitting increased rates of combustion, and, producing increasedevaporation.

fioorportion' 21in Fig. l, and 74 .at the rear floor portion'22,these'jets being arranged at the. slopes and directed in a; manner to\imdrive them downwardly toward the chute 23 and. ash chamber. As in theprior application, "these jets may be supplied with steam through pipes75 and 75,

steam constituting an efi'ective ash clearing medium; a special featureof improvement hereof-however bem ,the use ofllqllld of waterexpandinginto steam afford a more effective clearing action than steamor gas. It will be understood that the illustrated jets 74 and 74'represent an entire series thereof extendin across the furnace; The jetsmay be hand regulated by ordinary valves,-whi ch may be As a means ofclearing ashes'from the floor there are shown jets or nozzles 74 at thefront e jet pipes, as it turned on and off as needed, either to giveintermittent action, or continuous action of adjustable force. Fig. 3shows jets 74; atboth sides, supplied through steam or water pipes 751controllable either by hand or automatical y.-

An iniportant'feature hereof is the automatic regulation of the furnace,not by regulation of feed'of fuel or air, or of the combustion,butrather by controlling the eiiects following combustion, that is,controlling the resulting temperature of the furnace, or of the hot zonethereof and the products of combustion therein. This carrbe done invarious ways, for example by dilution of the prodnets of combustion forcooling purposes, or cooling the temperatures of the products ofcombustion in any other manner, for example through the described waterfloor adapted-to accumulate a shield of ashes, and the described jets toclear them off. Thus in Fig.

1 at the front side of the furnace, is shown,

. interposed in the jet pipe 75 a temperature controlled valve 77 Suchavalve is known on the market and may be for example of the Bristol type.It is operated by thermostat control to regulate the flow of steamorwater through the pipe, but I am unaware that such a valve has beenused for any purpose analogous to that herein disclosed. In acl-' ditionto the valve the control comprises a pyrometeror thermostat device 78,which may include an elongated thermo-couple 79 extended directly intothe hottest zone of the combustion chamber, with electric connec tions.80 to the motor portion of the -thermo valve 77. By this arrangementwhen the temperature has a tendency to rise too high the thermostatoperates through the automatic valve to increase or render more fre-,quent the ash clearing action, thus giving a greater extent of exposureof the water fioor, this developing an increased capacity tion.

to absorb radiant heat. thus taking downthe temperature and afiordingincreased evapora- The elements may be adjusted for example to maintaina normal'combustion temperature in the neighborhood of 1200 C. If

the temperature in the hot zouesh'ould rise substantially to 1300 C.this would have .a

tendency toproduce slagging difiiculties, and

the thermo control would operate to-decrease.

' would be incomplete combustion and loss of combustible passihgout'with the flue gases,

Y which would be corrected throughthethermo control device by shuttingdown on the jets so as to allow a; greater shielding of the floorashesfrom the fines or other points and returning them to the combustionchamber, as

means of returning to the combustionchamher, and delivering directlyupon thewater fioor, ashes from any convenient point, for

example collected in the ash space 19. Thus it might be importanttoeffect a quick shielding of the floor in connection with the controloperations. For this purpose a perfo rated pipe 82 is shown extendingthrough the lowest point of the ash space 19, this adapted to receiveashes and conduct them by a downwardly extendingpipe 83 to an ash'injection inlet 84. The drawing out of ashes from the space- 19 andforcin them into the combustion chamber may it} expeditedby an ejectordevice 85 controlled by exterior valve 86' and creating a'downwarddraftthrough the ash pipe 83.; I do not herein claim the broad conception ofrecovering I have disclosed and make broad claim thereto in copendingapplication No. 164.824 filed January 31, 1927, but Therein claim thespecific embodiment disclosed in Fig. 1 hereof consisting in directingflue ashes or other ashes directly upon a water floor, at its upperside, for the purpose of shielding or expediting the shielding of thefloor, by the ashes, from the radiant heat. I 1

.Next will be described my improvement in regulable superheating'ofgenerated steam. This involves circulation pipes directly exposed to theradiant heat, but susceptible of being more or less shielded to efi'ectregulation of the degree of superheat. For example the water tubes ofthe water floor hereof,,or a part thereof, may be employed, as asuperheater for the outgoing steam and this may deal with steam eitherdirectly from the main boiler or from another or ordinary superheater.Fig. 1 shows, above the boiler proper, and in the passage between thefirst and second passes, an ordinary superheater 88, receiving steamthrough pipe 89 from'the' drum 16. There is shown a downwardly extendingpipe 90. by which the steam from superheater 88 is conducted to thelower header 91 of the system of floor tubes 92 comprised in the rearfloor portion 22, these tubes constituting the superheater hereof,

and being interconnected by an upper header 93. both of the headers-91and 93 eing outside of the combustion'chamber. From the upper, headerextends a pipe 94 to a fitting 95 connected with a further upward pipe96 libleading to the final steam'outlet 97, and these connectingpipesmay obviously be jacketed,

or-suit'ably located to preserve the superheated condition of the steam.

' in Fig: l -th'ere has thus been shown a gen; eral combination whereinone water. floor- V portion2l is utilized for general control ofcombustionand furnace chamber temperature, while another water floorportion i 22 is employed for superheating outgoing steam.

operate to" absorb radiant heat audi -increaseevaporation, whilepreventing excessive temperatures and thus permitting-high rates ofcombustion. The rear fioor portion has these efi'ects, although notunder control of the furnace temperature,-wh ile the front floor,portion is under-control of the furnace temdesired control.

perature and canthus function to vett'ect the In some casesthe entirewater-floor, and all portions thereof, could be usedfor combustioncontr'ol,or in some cases theenti-re floor'could be usedfor superheating purposes; both uses being considered" to be novel, and thecombined-use of special and novel utility.

It will be understood from the above that -o the degree of superheatfrom the outgoing steam is regulable by regulating the shielding orclearing ofipf the rear floor portion 22 containing the superheatingfloor tubes 92.

'? Thus thegreater the shielding of the rear floor portion the less Willbe the heat abs-orntion by the steam circulating through the tubes,while the more effective or the more frequent the clearing of the ashes,the greater willbe the heat absorption and the heating efiect. Thisregulations may be effected by through jets of steam, gas or Water uponthe metal, silicon carbide, or other conducting covering or plate thenozzles being su pplied by pipes f which may be A the flow of steam,

" perature of theoutgoing steam exceeds the will and thus reduceiorcu-toff the floor clearing- I When the outgoing steam regulated by a valvein 'any desired-manner.

steam pipe 96, these elements connected by an electric cable'102," Thisthermo control device may be so adjusted that when the temdesiredtemperature the thermostat device operate toshut down the automaticvalve ets, permitting ashes to accumulate to shield 'the'floor andreduce the amount .of radiant heat absorbed in 4 the floor 'superheater.falls below the desired temperature the-reverse operation takes place,andthe increased absorption of radi- This forms a particularly-Tuseful.combination inasmuehas both floor portions.

100 isshown 'c ;m 1pris-y mg an elongated thermo couple IOLeXtend-a ingthrough the fitting,.95-into the. upgoin'g integer antheat tendstorestore ture. Thisgives an approximat-j'co'ntrol of superheatin'gwhich is entirelywill beiadvantag'eous in many can, if desired besupplemented by manual control.

Another feature shown in ig.' '1.i's-a -slag.

the desired automatic and s1tuat10ns,;-and I screen located in advanceof the boiler be- 1 tween the hot and reducing zon .bustion, chamber andthe outlet tothe boiler f This is not to be confused withthe 'lo'wermostes of the com-l tier of boiler tubes 104, shown spaced some;

what down from the main'tubes to permit access, for slagremoval. Thepresent-inn provement consists of a series of fan'ly widely spacedClIClllfltlOIl tubes a 105 constituting a f in effect a water screen forthe upward traveling gases, ashes and other products of'com-' ,bustion',these widely spaced 'tubes operating to absorb radiant heat from theproducts and ashes ascending between them, soas to chill the ashes andminimize or preventslagging screen 105 may becombined with This slag asystem of water tubes 106 at theunderside of the arch 14. The arch tubesmaybe closely spaced anddrawwater through, header.

106 from thedowncomer 31, while the wide-. 1y spacedwater screen tubes105 take off from the upper header 106 of the arch tubes, and slantupwardly to the rear of the boiler, where they are connected by a header.leading through pipe 107 to the steam spacesof the boiler. v

The various features thus referred to in connection with Figs. 1, 2 and3possess utility not merely in themselves, but inmany with the 7 casesgiving a combined operation I escribed water floor, as the several'features in many cases mutually cooperate',- g iving a joint action andimproving the eflicieneyfiof the apparatus. a mong manv possiblevariations there ,is

and rear water floor portions 2 symmetrically arranged, rather thanhaving I the special arrangement shown" in 'Fi gs land" 3, the chute orfloor'opeu'ings 23 continuously openand deliveringin'to the constantlysealed'ash pit 42H Nozzles 74 may supply fluid jets controlled byautomatic valves. 77 as before- The water'tubep'ol tions 33 curving downto the-headers 32? face 1 the floor opening and theash chamber soas toabsorb radiant heat and .cool the descend ing ashes and prevent slaggingthereof. The ash chamber 42 may be subdivided into small hopper shapechambers as shown in Fig. 5 by means'of; ash bridges 52. while operatedby-rack andfplnionfdeviees $34 the p g gates 45c m -b i t mittentl oneshown .in-Figs. 4 and 5 wherein the front 1 and22 are no workedautomatically or by hand; through sprocket 55. and 33 V blocks 35 aswith the" floor in Figs; land 2- A. downgoing water connection'32-Ymay;be

The floor and chute tubes may be covered by iron coverings: or

' dumped the ashes are discharged into a arranged from the upper floortube headers 26, to the lower headers 32, bringing water back for quickrecirculation without passing to the boiler. Ash pit doors 24 may beopened to give access for cleaning the floor portions 21 and 22.

. Fig.6 shows a variation wherein the water floor slopes downwardly fromone furnace wall substantiallyto the other, instead of having thecentral ash pit. .Jets at 111 may be employed for driving the ashes downthe inclined floor and the ashes may be received in a sealed ash chamber112 located inside the furnace wall line and beneath the combustionchamber. As before the ash chamber has a dumping gate 113 at the bottom, with'operating mechanism 114, and the gate discharges into a watersluce 115. In

this embodiment the ash chamber is at-a low .point and at one side andthus fairly shielded from the hot zone, so that, as indicated, the floorwater tubes do not have to be brought down into the chamber for coolingthe ash.-

In the Fig. 7 form the front and rear floor portions 21 and 22 containexposed water,

tubes 25 which are extended down at 33 into and substantially to thefoot of the ash chamber 42*; this symmetrical arrangement showing greatutility for certain conditions.

-Fig. 8 shows a variation wherein the two sides 118 of the furnacebottom are" steep enough to be self discharging by gravity. Thesesurfaces are shown at about 4:5", intended to be steeper than the angleof repose. These surfaces are covered with water circulation tubes 119.and these extend down'into the chute or, opening 120 by which thefurnace discharges into the sealed ash pit'121, the water tubesoperating to cool the pit and the ashes therein. The bottom of the ashchamber is provided with a dumping gate 122 operated with a mechanism123and when water sluice 124;. This figure shows a burner 126discharging into the hot zone of the combustion chamber and tubes 127constituting-a water wall to the furnace. The-ash chamber 121 may besubdivided into smallerchambers by ash bridges as before.

In Fig. 9 is shown an embodiment comprising a useful combination of awater bottom consisting of opposite, hopper shaped water cooled surfaces128 and a water screen. 1 The water tubes 128 shown at the left sideconnect with a header 129and from this header are taken widely spacedcirculation tubes 130 extending across the combustion chamber toconstitute the water screenlas stated, Each tube of the water screen mayconnect by an individual header with a plurality of upwardly extendingtubes 131 constituting a water-wall.

The bottom tubes 128 at the right side of the figure connect'with anexterior header 132 fromiwhich a-pipe 133. exten ds to the boiler.

The water cooled'hop'per bottom 128 discharges into a sealed ash pit 134which may generally follow the description given in con nection with theother figures.

In using herein such terms as thermostat or pyrometer in respect to theautomatic control of the furnace or of the superheater, it is intendedto cover any temperature or heat controlled means or device availablefor the purpose. The thermo-control means hereof may be considered asincluding any thermoash chamber, through which implements may beinserted for scraping or cleaning the accessible surfaces; while in Fig.6 doors 116 are shown in a difl erent locality for a similar purpose. i

An important feature of c'ontrol hereof in connection with the jets ornozzles 74 directed upon the bottom orfloor hereof is the availabilityof steam or. of liquid water for the jets, or change from one to theother. The use of Water in place of steam is particularly useful at peakloadsof service. rates into very forcible steam jets for clearing thefloor of ashes, thus permitting It evapogreater heat absorption andprevention'of excessive temperatures; but aside from that,

and irrespective of the water floor-[the water jets give the result of.diluting the combustion gases by steam and thus preventing excessivefurnace temperature, while at the same time absorbing the heat necessaryto convert the water to steam, and in that way lowering the temperature;so that at' times of peak load and combustion rate, by 3 opening up thewater jets all the drawbacks of excessive temperature may be obviated;and this operation may be automatioas already described. In using theterms floor and'bottom in this patent I intend to draw the distinctionthat a floor is specifically a bottom which is not inclined toosteeplyfo-r accumulation of ashes falling upon it.

Vhilm the following features are herein disclosed and were disclosed inmy said prior Patent 1,703,814 they are not herein claimed,

'but are made the subject of claim in my 00- pending application SerialNo. 342,039, filed February 23. 1929, namely, a water cooled arch abovethe fuel entrance of a furnace,

'especi ally a boiler furnace burning pulverized coal; also said archcomprising water. cn-culatlon tubes preferably with refractory wallmembers between them; also therefrac- .tory members bemgisupported onand depending between the tubes so as to leave the tubes effectivelyexposed, but preferably partially Shielded by. the refractory members;

also such Water cooledarch .above-thefuel entrance in combinatlonwltha,water cooled bottom beneath such entrance, with prefer-- ably the archand bottom flaring away from the injected fuel stream; also said watercooled archin combination with a slag screen ofrelatively widely spaced.water tub-es to which thewater arch delivers, said screen boiler. w

located'between the combustion zone and the There have thus beendescribed a newmeth-- od or system ofpulverizedfuel combustion and anapparatus or furnace for carrying out the same, embodying the principlesandattaining the advantages of the presentinvention. Since variousmatters of combination, arrangement, operation, construction and detailmay be modifiedewithout.departing from I the principles itis'notintended to limit the invention to such matters exceptso'far as,

set forth in the appendedclaims.

VVhatis claimed is:

1.' A pulverized fuel boiler furnace comprising a combustion chamberhaving a first or hot zone with uncooled refractory walls followed by aWater cooled zone between the hot zone and'the boiler and containingwater passages, a water cooled floor comprising circulation tubes, andcirculation connect-ions.

leading water fromthe boiler t'o the water floor, thence from the waterfloor to the water passages of the cooled zone, and thence to theboiler.

- '2. A pulverized fuel furnace comprising the walls of the combustionchamber, a'me-. b tallic water cooled floor beneath thecombustionchamber, an ash supply pocket and: an.

ash passage from the supply pocket to the chamber floor for conveyingand depositing fuel ashes and applying them directly upon' the floor toshield the same.'

3. A furnace as in claim 2 and wherein theash conveying means comprisesan ash pa s'- sage from an ash collecting pocket in the' boiler to thefloor and meansas an e]ector,

controllable to acceleratethe flow of ashes therein.

4. For the combustion ofpulverized fuel in suspension in air,,a furnaceof thelkind having a slag preventing bottom tothe combustion chambercomprising waterv circulation tubes and presenting toward the radiantheat a substantially closed heat absorbing bottom surface arranged at'anincline'discharging to an ash outlet; in which furnace the water cooledbottom comprises oppositely inclined bottom portions dischargingdownwardly to a relatively narrow and continuously open dischargeslot'extending substantially fromside. to side of the combustionchamber, andwith an eirteriorly sealed ash chamber below suchoutletreceiving the unthe discharge slot.

. ing the unslagged ashes,

row; common; outlet, and

slagged ashes, said ash chamber narrower than the combination chamberbut wider than 5. For the combustion of pulverized fuel in suspension inair, a. furnace of the kind having a Islag preventing bustion chambercomprising water circula-' tion tubes and presenting toward theradibottom surface arranged at a-dowmvard incline discharging to'anash-outlet; in which furnace the water cooled bottom comprisesoppositely inclined bottom portions dis-. charging downwardly to arelatively narrow-commonoutlet, andwith an exteriorly sealed lashchamber-below such outlet receivand the water tubes of the bottom beingcontinued at both sides to extend downwardly into the outlet and receiveradiantheat from the descending ashes.- 1 q 6-; For the combustion ofpulverized fuel in suspension in air, a furnace of the'kindhavingaslagpreventing bottom to the combustion chamber comprising watercirculation tubes and presenting toward the radiant bottom-to thecomant-heat a substantially closed heat absorbing heat a substantiallyclosed heat absorbing,

er to receive radiant heat from theashes i comprising water circulationtubes for heat 1 absorption and arranged at an incline to an ash.outlet, and means to inject pulverized fuel andair above such bottom;in which furnace the. water cooled bottonr comprises oppositely inclinedbottom portions" discharging ashes downwardly at both sides to arelatively narrow and continuously open bottom-outlet, and with ane'xteriorly vsealed ash chamberbelow such outlet re'ceiv ing the'unslagged ashes, a 'movable gate ad- ]ustable in such bottom outlet tovarythe width of the opening, and means for'holding the adjustment. 1 V

l 8. For the combustion of pulverizedfuel in suspension. in air, aboiler or other furnace of the kind haviuga slag preventing bottomto'the combustion chamber comprising water circulation tubes andpresenting toward the 'radiantheat a substantially closed heat absorblng bottom surface arranged at an incline discharging to an ashoutlet, and means for injecting pulverized fuel-and air into thechamber; in which furnace the water cooled bottom comprises oppositelyinclined water cooled bottom portions discharging unslagged ashdownwardly to an open outlet slot extendin across the chamber, and belowsuch out et an exteriorl chamber provided with ash ridges dividing itinto hopper shape subchambers, the top edges of the bridges beingsubstantially lower than the combustion chamber bottom and the severalpockets having separate dumping means;

In testimony whereof, 1 have aed my signature hereto.

- sealed ash'

